A new survey by Pew Research Center reveals that relying on Twitter to gauge public opinion might not be too smart: the reaction on Twitter to big national and political news seems to differ wildly from that measured by surveys.

Perhaps unsurprisingly, Twitter reactions generally tend to be more liberal than the national average. Tracing news stories over the past year, Pew saw that Twitter reactions to stories like the federal court ruling a California law banning same-sex marriage was unconstitutional were generally very positive. And during the presidential debates, Twitter opinion was far more critical of Romney than the general public was.

It's not all fluffy liberal sentiment, though. Twitter users were generally far, far more critical of Obama's second inaugural address, for instance.

But what does that all mean? Plainly, that Twitter users—particularly those who tweet about news—just aren't representative of the public. Instead, they're their own separate demographic: typically younger, and Democrat-supporting. All of which is, of course, fine—but it's a good reminder that what you read on Twitter isn't 100 percent representative of what's going on in the real world. [Pew]